Carpet products and processes for making same using latex coating compositions

ABSTRACT

Disclosed are carpet products comprising at least one substrate and at least one adhesive layer associated with the at least one substrate, the adhesive layer being formed from a latex coating composition comprising (a) a first copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene; and (b) a second copolymer of at least styrene and butadiene, wherein the first and second copolymers are colloidally dispersed in an aqueous medium comprising a surfactant. The carpet products are particularly durable exhibiting high tuft bind values.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Appl. No. 61/599,127, filed Feb. 15, 2012, the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to latex coating compositions comprising a vinyl ester/ethylene copolymer dispersion and a styrene/butadiene copolymer dispersion useful for forming carpet products as well as to processes for forming such carpet products.

BACKGROUND OF THE INVENTION

Most conventional carpets comprise a primary backing with yarn tufts in the form of cut or uncut loops extending upwardly from this backing to form a pile surface. For tufted carpets, the yarn is inserted into a primary backing (frequently a woven or nonwoven material) by tufting needles and a precoat (i.e., a binder) is applied thereto.

Most residential and commercial carpets are also manufactured with a woven scrim (typically made from polypropylene), also referred to as a secondary backing, attached to the back of the carpet to provide dimensional stability. The scrim is attached to the precoated carpet back with another binder formulation typically referred to as a skipcoat or adhesive coating. The skipcoat is applied to the scrim, and the scrim is then applied to the precoated backing of the carpet before the assembled carpet elements are sent into a curing oven. The purpose of the skipcoat or adhesive coating is to provide a layer of material which will adhere the woven scrim to the back of the carpet.

For both the precoat and the skipcoat, the physical properties of the binders are important to their successful utilization as carpet coatings. In this regard, there are a number of important requirements which must be met by such coatings. The coating must be capable of being applied to the carpet and dried using the processes and equipment conventionally employed in the carpet industry for latex coating. The binder composition must provide excellent adhesion to the pile fibers to secure them firmly in the backing. The coating will also typically have a high loading of fillers such as calcium carbonate, clay, aluminum trihydrate, barite, feldspar, cullet, fly ash and/or recycled carpet backing.

The binders in coating compositions for carpet products are frequently emulsion polymers, i.e., latex dispersions, which can comprise copolymers of vinyl esters (such as vinyl acetate) and ethylene. Binders and carpet coating compositions based on vinyl ester/ethylene copolymers are disclosed, for example, in U.S. Pat. Nos. 4,735,986; 5,026,765; 5,849,389 and 6,359,076 and in U.S. Publication No. 2005/0287336, the entireties of which are incorporated herein by reference. These copolymers are prepared by polymerizing appropriate co-monomers in an aqueous emulsion. Such emulsions or resulting dispersions can be stabilized by adding conventional surfactants (anionic, nonionic, or cationic) as emulsifiers. Such emulsions or dispersions may also be stabilized by including protective colloids such as those based on polyvinyl alcohols (PVOH), ionically modified starches, water-soluble starches, starch ethers, polyacrylic acid, carboxymethyl cellulose, natural gums, gelatin, synthetic polymers, or water-soluble cellulose ethers such as hydroxyethyl cellulose (HEC).

Notwithstanding the availability of a variety carpet coating and adhesive compositions based on stabilized vinyl acetate/ethylene (VAE) latex binders, it would be advantageous to identify and select specific types of such binders that exhibit a desirable balance of properties which make them especially useful in preparing textile structures such as carpet products.

The need therefore exists for improved VAE-based coating compositions and processes for making such coating compositions having desired binding strength characteristics for carpet manufacturing applications.

SUMMARY OF THE INVENTION

It has now been discovered that by blending certain vinyl ester/ethylene copolymer dispersions, preferably vinyl acetate/ethylene (VAE) copolymer dispersions, with styrene/butadiene (SB) copolymer dispersions, latex coating compositions may be prepared having especially desirable physical properties, rendering them well-suited for use in adhesive compositions such as precoat and/or skipcoat binders in carpet manufacture. In particular, carpet products having particularly high tuft bind values may be formed using the processes and latex coating compositions of the present invention.

In one embodiment, the present invention is directed to a carpet product, e.g., a tufted or woven carpet product, comprising at least one substrate and at least one adhesive layer associated with said at least one substrate, e.g., directly or indirectly bound to the substrate, said adhesive layer being formed from an adhesive composition comprising a latex coating composition comprising: (a) a first copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene; and (b) a second copolymer of at least styrene and butadiene, wherein the first and second copolymers are colloidally dispersed in an aqueous medium comprising a surfactant. The latex coating composition may be incorporated into an adhesive composition that functions as a precoat or as a skipcoat binder or as both. Accordingly, the substrate may comprise a primary backing or a secondary backing. The carpet products of the invention preferably are particularly durable exhibiting tuft bind values greater than 20 N, e.g., greater than 27 N.

In one embodiment, the latex coating composition functions as a precoat for binding carpet fibers, e.g., as tufts, to a primary backing. For example, in one embodiment, the invention is a process for forming a carpet product, the process comprising the steps of: (a) providing an adhesive composition comprising a latex coating composition comprising: (i) a first copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene; and (ii) a second copolymer of at least styrene and butadiene, wherein the first and second copolymers are colloidally dispersed in an aqueous medium comprising a surfactant; (b) contacting carpet fibers, e.g., tufted yarn, with a primary backing material, e.g., a primary tufting substrate or woven material; (c) applying the adhesive composition to the carpet fibers and the primary backing material; and (d) drying the adhesive composition under conditions effective to adhere the carpet fibers to the primary backing material.

In another embodiment, optionally combined with the above process, the adhesive composition acts as a skipcoat binder in the manufacture of a carpet product. For example, in one embodiment, the invention is to a process for forming a carpet product, the process comprising the steps of: (a) providing an adhesive composition comprising a latex coating composition comprising: (i) a first copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene; and (ii) a second copolymer of at least styrene and butadiene, wherein the first and second copolymers are colloidally dispersed in an aqueous medium comprising a surfactant; (b) providing a primary carpet layer comprising yarn tufted into a primary backing; (c) applying the adhesive composition to at least one of the primary carpet layer or a secondary backing; (d) contacting the primary carpet layer with the secondary backing; and (e) drying the adhesive composition under conditions effective to adhere the primary carpet layer to the secondary backing. The primary carpet layer optionally is formed by a process employing a precoat coating composition, which optionally comprises the same or similar latex coating composition employed in the adhesive composition that is used to secure the primary carpet layer to the secondary backing.

DETAILED DESCRIPTION OF THE INVENTION

The invention, in one embodiment, is directed to latex coating compositions useful as coating and adhesive compositions incorporated into textile structures, e.g., carpet products. The latex coating compositions comprise a blend of a first copolymer, preferably in a first copolymer dispersion, and a second copolymer, preferably in a second copolymer dispersion. The first copolymer is a copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms, preferably vinyl acetate, and ethylene, and the second copolymer is a copolymer of at least styrene and butadiene. The latex coating compositions surprisingly and unexpectedly provide particularly desirable adhesive characteristics, in particular tuft bind values, when used in forming textiles. The latex coating compositions are particularly useful for use as precoats or skipcoats in the formation of carpet products. The invention is accordingly also directed to carpet products formed using the inventive latex coating compositions and to processes for forming such carpet products.

The relative amounts of the first copolymer and the second copolymer in the blended latex coating composition may vary depending, for example, on the desired characteristics for the carpet product as well as whether the latex coating composition is intended for use in a precoat, a skipcoat or both. In one embodiment, the blended latex coating composition comprises the first copolymer in an amount from 30 to 99 wt. %, e.g., from 40 to 75 wt. %, and the second copolymer in an amount from 1 to 70 wt. %, e.g., from 25 to 60 wt. %, based on the total weight of all copolymers in the blended latex coating composition. Latex coating compositions for use in a precoat preferably comprise greater concentrations of the first copolymer, optionally comprising the first copolymer in an amount from 50 to 99 wt. %, e.g., from 70 to 90 wt. %, and the second copolymer in an amount from 1 to 50 wt. %, e.g., from 10 to 30 wt. %. Latex coating compositions for use in a skipcoat preferably comprise greater concentrations of the second copolymer, and may comprise, for example, the first copolymer in an amount from 25 to 75 wt. %, e.g., from 25 to 50 wt. %, and the second copolymer in an amount from 25 to 75 wt. %, e.g., from 50 to 75 wt. %, based on the total weight of all copolymers in the latex coating compositions.

In some embodiments, the latex coating compositions of the invention may comprise one or more external crosslinkers. Suitable external crosslinkers include carbonates such as ammonium zirconium carbonate (AZC) and potassium zirconium carbonate (KZC). The external crosslinker may be added to the first dispersion, the second dispersion, or to both the first and second dispersion, optionally before or after blending of the first and second dispersions to form the blended latex coating composition. If present, the external crosslinker may be present in the latex coating composition in an amount from 1 to 10 wt. %, e.g., from 3 to 10 wt. %, based on the total weight of the blended latex coating composition.

Since they are preferably formed in separate dispersions and then blended together, the second copolymer preferably is not intimately mixed with the first copolymer, although it is contemplated that the external crosslinker, if present, may effectively crosslink carboxyl groups on the first copolymer with carboxyl group on the second copolymer. To the extent that internal crosslinkers are employed, it is preferred that such crosslinkers act to crosslink the first copolymer with itself and/or the second copolymer with itself, but do not act to internally crosslink the first copolymer with the second copolymer. In one embodiment, both the first and second copolymers, respectively, include internal crosslinkers, which may be the same or different type of crosslinker, but such crosslinkers do not internally crosslink the first copolymer with the second copolymer. In another embodiment, the first and second copolymer dispersions and the resulting blended latex coating composition of the invention are substantially free of internal and/or external crosslinkers.

As noted, the first and second copolymers used to form the latex coating compositions described herein are preferably made separately in a first dispersion and a second dispersion, respectively, which are blended together to form the inventive latex coating composition. The first and second dispersions preferably are present in the blended latex coating composition in an amount sufficient to impart particularly good carpet strength.

The extent or tenacity to which the yarn is affixed to a carpet backing material is referred to as “tuft bind” strength. Carpets with sufficient tuft bind strength exhibit good wear resistance and have longer service lives. In order to have good performance characteristics, the adhesive backing material should substantially penetrate the yarn (fiber bundle) exposed on the backside of the primary backing material and should substantially consolidate individual fibers within the yarn. Good penetration of the yarn and consolidation of the fibers leads to good abrasion resistance. Moreover, in addition to good tuft bind strength and abrasion resistance, the adhesive material preferably imparts or allows good flexibility to the carpet in order to facilitate installation of the carpet. In a preferred embodiment, the blended latex coating composition may be used in an adhesive composition, e.g., carpet precoat or skipcoat binder, to form a carpet composition having a tuft bind value greater than 15 N, e.g., greater than 20 N or greater than 27 N, as determined by ASTM D-1335. For cut pile carpet, the tuft bind value preferably exceeds 2.3 lbs f (10.2 N). For loop carpets, the tuft bind value preferably exceeds 3.5 lbs f (15.6 N), more preferably exceeds 6.25 lbs f (27.8 N) and most preferably exceeds 10 lbs f (44.5 N).

Since tuft bind values may vary depending on carpet type, the tuft bind strength may be characterized as a “tuft bind percentage” relative to a similar carpet formed using a coating composition containing the first dispersion (not blended with the second dispersion). In this aspect, the blended latex coating compositions of the invention may provide carpeting having a tuft bind percentage greater than 125%, greater than 150%, greater than 175% or greater than 200%.

The first and second dispersions containing the first and second copolymers, respectively, can be prepared using conventional emulsion polymerization procedures. Such procedures are described in general, for example, in U.S. Pat. No. 5,849,389, the entirety of which is incorporated herein by reference, as well as in Chorng-Shyan Chern, Principles and Applications of Emulsion Polymerization, John Wiley and Sons Inc. (2008), the entirety of which is incorporated herein by reference.

In forming the first and second dispersions, the respective monomers can be polymerized in an aqueous medium under pressures not exceeding 100 atmospheres in the presence of a catalyst and at least one emulsifying agent. For either dispersion, the aqueous system can be maintained by a suitable buffering agent at a pH of from 2 to 6 or from 4 to 6, with the catalyst being added incrementally or continuously. For the first dispersion, a vinyl ester, e.g., vinyl acetate, and 50% to 75% of the other co-monomers, if any, can be suspended in water and thoroughly agitated in the presence of ethylene under the working pressure to effect solution of the ethylene in the mixture up to the substantial limit of its solubility under the conditions existing in the reaction zone. The vinyl acetate and other optional co-monomers can then be gradually heated to polymerization temperature. In some embodiments, either or both the first dispersion and/or the second dispersion or the resulting blended latex coating composition of the invention are free of, or are substantially free of, colloidal stabilizers such as polyvinyl alcohol, optionally comprising less than 1.5 pphm polyvinyl alcohol, less than 1.0 pphm polyvinyl alcohol, or less than 0.5 pphm polyvinyl alcohol, which has now been discovered to be generally incompatible with SB dispersions. In other aspects, either or both the first dispersion and/or the second dispersion or the resulting blended latex coating composition of the invention comprises less than 1.0 wt. % polyvinyl alcohol, or less than 0.5 wt. % polyvinyl alcohol, based on the total weight of the monomers. It is contemplated, however, that some protective colloids, such as hydroxyethyl cellulose, may be compatible with SB dispersions.

The homogenization period is generally followed by a polymerization period during which the catalyst, which comprises a main catalyst or initiator, and may include an activator, is added incrementally or continuously together with the remaining co-monomers, if any. The monomers employed may be added either as pure monomers or as a premixed emulsion.

Following polymerization, the solids content of the resulting first and/or second dispersions can be adjusted to the level desired by the addition of water or by the removal of water by distillation. Generally, for both the first and second dispersion, the desired level of polymeric solids content is from 40 to 70 weight percent, based on the total weight of the respective dispersion, from 40 to 60 weight percent or from 45 to 55 weight percent.

The particle size of the first dispersion or the second dispersion, or the resulting blend of the first and second dispersions, can be regulated by the quantity of non-ionic or anionic surfactants employed. To obtain smaller particles sizes, greater amounts of surfactants are used. As a general rule, the greater the amount of the surfactant employed, the smaller the average particle size.

The dispersions and coating compositions described herein optionally are substantially free of alkylphenol ethoxylates (APEs). For purposes of this invention, such dispersions and coating compositions are considered to be substantially free of APEs if they contain less than 500 wppm of APEs. In other embodiments, the dispersion, e.g., either the first dispersion, the second dispersion, or the resulting blended latex dispersion of the invention may comprise a minor amount of APEs.

First Dispersion

The first dispersion preferably is formed by the emulsion polymerization of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene, and optionally one or more additional co-monomers. A non-limiting list of examples of such alkanoic acids includes vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl-2-ethyl-hexanoate, vinyl isooctanoate, vinyl nonate, vinyl decanoate, vinyl pivalate, vinyl versatate, and mixtures thereof. Of the foregoing, vinyl acetate is a preferred monomer because of its ready availability and low cost. Preferred monomer combinations for the first copolymer include vinyl acetate/ethylene, vinyl acetate/vinyl propionate/ethylene, vinyl acetate/vinyl neodecanoate/ethylene, vinyl acetate/ethylene/vinyl chloride.

Most preferably, the vinyl ester, e.g., vinyl acetate, content of the first copolymer used in this embodiment will range from about 70 to 90 pphm, e.g., from 72 pphm to 88 pphm, from 75 pphm to 95 pphm, from 75 pphm to 85 pphm, or from about 78 pphm to 82 pphm (parts per hundred based on total monomers in the copolymer).

Generally, the ethylene content of the first copolymer should be selected to provide a latex coating composition that is especially effective in formulating adhesive compositions that provide desirably high binding strength. In some embodiments, the ethylene will comprise from 10 pphm to 30 pphm of the first copolymer, e.g., from 10 to 25 pphm, from 12 pphm to 20 pphm, or from 18 to 22 pphm. More preferably, ethylene will generally comprise from 5 pphm to 25 pphm of the first copolymer, e.g., from 5 to 20 pphm or from 8 to 18 pphm. More preferably, ethylene will be present in the first copolymer in an amount ranging from 8 pphm to 16 pphm.

If the first copolymer further comprises a third co-monomer, the first copolymer may comprise the third monomer, for example, in an amount from 0.1 to 10 pphm, e.g., from 0.1 to 5 pphm. Such optional co-monomers. for example, may be selected from the group consisting of vinyl halides such as vinyl chloride, ethylenically unsaturated acids, or the salts thereof, ethylenically unsaturated monomers having at least one amide, epoxy, hydroxyl, N-methylol, trialkoxysilane or carbonyl group, and combinations of two or several monomers from any of said third co-monomer types. Optional co-monomers can also be selected from the group consisting of vinyl esters which are not vinyl acetate, alpha-olefins which are not ethylene, vinyl aromatics, esters of ethylenically unsaturated monocarboxylic acids, and diesters of ethylenically unsaturated dicarboxylic acids.

Preferably, the first copolymer is formed in a surfactant stabilized emulsion polymerization process rather than a protective colloid stabilized polymerization process. As a result, the average particle size of the first copolymer tends to be smaller than copolymers formed in the presence of protective colloids. In exemplary embodiments, the first copolymer has an average particle size from 50 to 500 nm, e.g., from 100 to 400 nm, from 150 to 350 nm, or from 200 to 320 nm, as determined by a 90 Plus Particle Size Analyzer (Brookhaven Instruments) using a 35 mW solid state laser of 658 nm wavelength at room temperature.

Optionally, the first copolymer further comprises a co-monomer that acts as an internal crosslinker. For example, the first copolymer optionally further comprises a polyethylenically unsaturated co-monomer selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, diallyl maleate, diallyl fumarate, divinyl benzene, diallyl phthalate, silanes and glycidyl methacrylate (GMA). The incorporation of one or more of these co-monomers may beneficially increase branching or crosslinking, increasing molecular weight and improving performance.

In some embodiments, the first copolymer includes a cross-linking co-monomer selected from α,β-ethylenically unsaturated C₃-C₁₀ mono-carboxylic acids, α,β-ethylenically unsaturated C₄-C₁₀ di-carboxylic acids and the anhydrides thereof, and the C₁-C₁₈ alkyl half-esters of the α,β-ethylenically unsaturated C₄-C₁₀ di-carboxylic acids. Exemplary co-monomers of this type include acrylic acid and methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid and the C₄-C₈ alkyl half esters of maleic acid.

In another embodiment, the first copolymer includes a cross-linking co-monomer selected from ethylenically unsaturated silane compounds. Exemplary ethylenically unsaturated silane co-monomers are disclosed, for example, in PCT Publ. WO 2011/139267, the entirety of which is incorporated herein by reference. This co-monomer can generally correspond to a substituted silane of the structural Formula I:

in which R denotes an organic radical olefinically unsaturated in the ω-position and R¹, R² and R³, which may be identical or different, denote halogen, preferably chlorine, or the group —OZ, Z denoting hydrogen or primary or secondary alkyl or acyl radicals optionally substituted by alkoxy groups.

Suitable unsaturated silane compounds of the Formula I are preferably those in which the radical R in the formula represents an ω-unsaturated alkenyl of 2 to 10 carbon atoms, particularly of 2 to 4 carbon atoms, or an ω-unsaturated carboxylic acid ester formed from unsaturated carboxylic acids of up to 4 carbon atoms and alcohols carrying the Si group of up to 6 carbon atoms. Suitable radicals R¹, R², R³ are preferably the group —OZ, Z representing primary and/or secondary alkyl radicals of up to 10 carbon atoms, preferably up to 4 carbon atoms, or alkyl radicals substituted by alkoxy groups, preferably of up to 3 carbon atoms, or acyl radicals of up to 6 carbon atoms, preferably of up to 3 carbon atoms, or hydrogen. Most preferred unsaturated silane co-monomers are vinyl trialkoxy silanes.

Examples of preferred silane compounds of the Formula I include vinyltrichlorosilane, vinylmethyldichlorosilane, γ-methacryloxypropyltris(2-methoxyethoxy)silane, vinylmethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyldiethoxysilanol, vinylethoxysilanediol, allyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltriacetoxysilane, trimethylglycolvinylsilane, γ-methamloxypropyltrimethylglycolsilane, γ-acryloxypropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane.

Another group of cross-linking co-monomers is composed of ethylenically unsaturated monomers containing epoxy groups, such as, for example, allyl glycidyl ether, methacryloyl glycidyl ether, butadiene monoepoxides, 1,2-epoxy-5-hexene, 1,2-epoxy-7-octene, 1,2-epoxy-9-decene, 8-hydroxy-6,7-epoxy-1-octene, 8-acetoxy-6,7-epoxy-1-octene, N-(2,3-epoxypropyl)acrylamide, N-(2,3-epoxypropyl)methacrylamide, 4-acrylamidophenyl glycidyl ether, 3-acrylamidophenyl glycidyl ether, 4-methacrylamidophenyl glycidyl ether, 3-methacrylamidophenyl glycidyl ether, N-glycidyloxymethylacrylamide, N-glycidyloxypropylmethacrylamide, N-glycidyloxyethylacrylamide, N-glycidyloxyethylmethacrylamide, N-glycidyloxypropylacrylamide, N-glycidyloxypropylmethacrylamide, N-glycidyloxybutylacrylamide, N-glycidyloxybutylmethacrylamide, 4-acrylamidomethyl-2,5-dimethylphenyl glycidyl ether, 4-methacrylamidomethyl-2,5-dimethylphenyl glycidyl ether, acrylamidopropyldimethyl(2,3-epoxypropyl)ammonium chloride, methacrylamidopropyldimethyl(2,3-epoxypropyl)ammonium chloride, and glycidyl methacrylate.

The aforementioned cross-linking co-monomers will be generally present in the first copolymer, if at all, in an amount from 0.05 pphm to 5 pphm, e.g., 0.05 to 1 pphm or from 0.05 pphm to 0.5 pphm. More preferably, such polyethylenically unsaturated co-monomer(s)/cross-linker(s) will be used in the first copolymer, if at all, in amounts from 0.2 pphm to 0.8 pphm.

The first copolymer prepared herein and used in the latex coating compositions may have both amorphous and crystalline ethylene segments. The level of amorphous ethylene segments in the copolymer is determined by the glass transition temperature (Tg) of the copolymer.

In accordance with one embodiment, the first copolymer of the dispersions produced herein for use in carpet manufacture may be prepared to have a Tg of from about −10° C. to about 20° C., e.g., from about −10° C. to about 15° C. In some aspects, the Tg may range from −5° C. to 5° C. In other aspects, the first dispersion may be prepared to have a Tg of from about +5° C. and about +15° C., preferably between about +8° C. to +10° C. Tg of the first copolymer can be controlled by adjusting the ethylene content, i.e., generally the more ethylene present in the polymer relative to other co-monomers, the lower the Tg.

The dispersions comprising the first copolymer hereinbefore described can be prepared using conventional emulsion polymerization procedures which result in the preparation of dispersions in aqueous latex form. Such procedures are described, for example, in U.S. Pat. No. 5,849,389, the disclosure of which is incorporated herein by reference in its entirety.

In a typical polymerization procedure, the vinyl ester, preferably vinyl acetate, ethylene, and optionally one or more additional third co-monomers can be polymerized in an aqueous medium under pressures not exceeding 100 atmospheres in the presence of a catalyst and at least one emulsifying agent. The aqueous system can be maintained by a suitable buffering agent at a pH of 2 to 6, with the catalyst being added incrementally or continuously. More specifically, vinyl acetate and 50% to 75% of the other co-monomer(s), if any, can be suspended in water and thoroughly agitated in the presence of ethylene under the working pressure to effect solution of the ethylene in the mixture up to the substantial limit of its solubility under the conditions existing in the reaction zone. The vinyl ester, e.g., vinyl acetate, and other co-monomers, if any, can then be gradually heated to polymerization temperature.

As discussed above, the homogenization period is generally followed by a polymerization period during which the catalyst, which comprises a main catalyst or initiator, and may include an activator, is added incrementally or continuously together with the remaining co-monomers, if any, e.g., one or more third co-monomers. If employed, the one or more third co-monomers may be added either as pure monomer or as a premixed emulsion.

Suitable polymerization catalysts for forming the first dispersion include the water-soluble free-radical-formers described above and generally used in emulsion polymerization, such as hydrogen peroxide, sodium persulfate, potassium persulfate and ammonium persulfate, as well as tert-butyl hydroperoxide, optionally in amounts from 0.01% and 3% by weight, preferably 0.01% and 1% by weight based on the total amount of the emulsion. The catalysts can be used together with reducing agents such as sodium formaldehyde-sulfoxylate, ferrous salts, sodium dithionite, sodium hydrogen sulfite, sodium sulfite, sodium thiosulfate, ascorbic acid, erythorbic acid, or salts thereof, as redox catalysts in amounts from 0.01% to 3% by weight, preferably from 0.01% to 1% by weight, based on the total amount of the emulsion. The free radical-formers can be charged in the aqueous emulsifier solution or be added during the polymerization in doses. In a preferred embodiment, the reducing agent Bruggolite FF6™ is employed in the polymerization process. FF6 comprises three sulfur-based reducing agents: (i) 2-Hydroxy-S-Sulfinatoacetic acid, di-sodium salt (50-60%); (ii) sodium sulfite (30-35%); and (iii) 2-Hydroxy-2-sulfonatoacetic acid, di-sodium salt (10-15%).

The manner of combining the polymerization ingredients can be by various known monomer feed methods, such as, continuous monomer addition, incremental monomer addition, or addition in a single charge of the entire amounts of monomers. The entire amount of the aqueous medium with polymerization additives can be present in the polymerization vessel before introduction of the monomers, or alternatively, the aqueous medium, or a portion of it, can be added continuously or incrementally during the course of the polymerization.

The emulsion polymerization processes used to prepare the first copolymer in aqueous latex form is preferably carried out in the presence of a stabilization system which comprises one or more anionic and/or nonionic surfactants as emulsifiers.

Suitable nonionic surfactants that can be used as emulsifiers in the emulsion stabilizing system of the coating compositions herein include polyoxyethylene condensates. Such ethoxylated nonionic surfactants used to stabilize the binder dispersions of the present invention preferably do not include ethoxylated nonionics based on alkyl phenols. Exemplary polyoxyethylene condensates that can be used include polyoxyethylene aliphatic ethers, such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; polyoxyethylene alkaryl ethers, such as polyoxyethylene nonylphenol ether and polyoxyethylene octylphenol ether; polyoxyethylene esters of higher fatty acids, such as polyoxyethylene laurate and polyoxyethylene oleate, as well as condensates of ethylene oxide with resin acids and tall oil acids; polyoxyethylene amide and amine condensates such as N-polyoxyethylene lauramide, and N-lauryl-N-polyoxyethylene amine and the like; and polyoxyethylene thio-ethers such as polyoxyethylene n-dodecyl thio-ether.

Nonionic surfactants that can be used also include a series of surface active agents available from BASF under the Pluronic™ and Tetronic™ trade names. Pluronic surfactants are ethylene oxide (EO)/Propylene oxide (PO)/ethylene oxide block copolymers that are prepared by the controlled addition of PO to the two hydroxyl groups of propylene glycol. EO is then added to sandwich this hydrophobe between two hydrophilic groups, controlled by length to constitute from 10% to 80% (w/w) of the final molecule. Pluronic surfactants are PO/EO/PO block copolymers prepared by adding EO to ethylene glycol to provide a hydrophile of designated molecular weight. PO is then added to obtain hydrophobic blocks on the outside of the molecule. Tetronic surfactants are tetra-functional block copolymers derived from the sequential addition of PO and EO to ethylene-diamine. Tetronic surfactants are produced by the sequential addition of EO and PO to ethylene-diamine. In addition, a series of ethylene oxide adducts of acetyleneic glycols, sold commercially by Air Products under the Surfynol™ trade name, are suitable as nonionic surfactants.

Suitable anionic surfactants that can be used as emulsifiers in the binder latex components of the carpet coating compositions described herein include alkyl aryl sulfonates, alkali metal alkyl sulfates, sulfonated alkyl esters and fatty acid soaps. Specific examples include sodium dodecylbenzene sulfonate, sodium butylnaphthalene sulfonate, sodium lauryl sulfate, disodium dodecyl diphenyl ether disulfonate, N-octadecyl sulfosuccinate and dioctyl sodiumsulfosuccinate. The surfactants are employed in amounts effective to achieve adequate emulsification of the polymer in the aqueous phase and to provide desired particle size and particle size distribution. Other ingredients known in the art to be useful for various specific purposes in emulsion polymerization, such as, acids, salts, chain transfer agents, and chelating agents, also may be employed in the preparation of the polymer. For example, if the polymerizable constituents include a monoethylenically unsaturated carboxylic acid monomer, polymerization under acidic conditions (pH 2 to 7, preferably 2 to 5) is preferred. In such instances the aqueous medium can include those known weak acids and their salts that are commonly used to provide a buffered system at the desired pH range.

Conventionally, various protective colloids have been used to stabilize vinyl acetate/ethylene emulsions of the type hereinbefore described, instead of or in addition to the surfactant emulsifiers. For the dispersions to be used in textile structures, up to about 2 wt % of a protective colloid such as cellulose ether or other conventional protective colloid-forming materials may be used. The use of hydroxyethyl cellulose, for example, may be acceptable or desired in combination with one or more surfactants. Dispersions used for this purpose can also be substantially free of protective colloids. In some embodiments, the first dispersion, second dispersion, and/or the blended latex coating compositions of the invention are free or substantially free of polyvinyl alcohol, optionally comprising less than 1.5 pphm polyvinyl alcohol, less than 1 pphm polyvinyl alcohol, or less than 0.5 pphm polyvinyl alcohol. In other embodiments, a small amount of polyvinyl alcohol may be employed so long as it does not render the first dispersion incompatible with the second dispersion. For example, in some embodiments, the first dispersion may comprise from about 1 to 2 wt % polyvinyl alcohol in latex coating compositions for use in forming textile structures such as tufted carpets.

As indicated above, the first copolymer within the dispersions prepared herein may generally have a mean particle diameter, dw, ranging from 50 to 500 nm, e.g., from 100 to 400 nm, from 150 to 350 nm, from 150 to 200 nm or from 200 to 320 nm, as determined by a 90 Plus Particle Size Analyzer (Brookhaven Instruments) using a 35 mW solid state laser of 658 nm wavelength at room temperature. The copolymer within the dispersions prepared for use with tufted carpets may have a mean particle diameter, dw, ranging from 200 to 600 nm. The viscosity of the dispersion may vary greatly, and in some aspects ranges from 50 to 400 mPas, or may be greater, potentially ranging from 400 to 1,600 mPas, as measured with a Brookfield viscometer at 25° C.

Second Dispersion

The second dispersion preferably is formed by the emulsion polymerization of at least styrene and butadiene (SB), and optionally one or more additional co-monomers such as an acrylonitrile (SBA) or an acrylic co-monomer.

As described above with respect to the first copolymer, the second copolymer optionally further comprises a co-monomer that acts as an internal crosslinker. For example, the second copolymer optionally further comprises a polyethylenically unsaturated co-monomer selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, diallyl maleate, diallyl fumarate, divinyl benzene and diallyl phthalate. Preferred co-monomers of this type included diallyl maleate, diallyl fumarate and diallyl phthalate. This type of polyethylenically unsaturated co-monomer will be generally present in the second copolymer, if at all, in an amount from 0.05 pphm to 0.5 pphm. More preferably, such polyethylenically unsaturated co-monomer(s)/cross-linker(s) will be used in the second copolymer, if at all, in amounts from 0.1 pphm to 0.3 pphm.

Processes for manufacturing the second dispersion prior to blending may vary depending on whether the second polymer is SB or SBA. Generally, such second dispersions may be formed through well-known emulsion polymerization techniques, exemplary processes for which are disclosed, for example, in U.S. Pat. Nos. 5,288,787; 5,326,853; 5,362,798; and 6,365,647, the entireties of which are incorporated herein by reference. Catalysts used in forming the second dispersion may be selected from those described above in connection forming the first dispersion.

The raw materials used to form the second dispersion, for example, typically include the monomers (styrene and butadiene for SB or styrene, butadiene and acrylonitrile for SBA), water, an emulsifier, an initiator system, a modifier, a free radical scavenger (e.g., dimethyl dithiocarbamate or diethyl hydroxylamine) and a stabilizer system. The polymerization process may be performed batch wise or continuously. In a continuous process, the monomers are metered into the reactor chains and emulsified with the emulsifiers and catalyst. The initiator system may be a redox reaction between, for example, chelated iron and an organic peroxide using a reducing agent, e.g., sodium formaldehyde sulfoxide (SFS). Alternatively, potassium peroxydisulfate may be used as the initiator. The process may be conducted as a cold polymerization process or a hot polymerization process. A mercaptan chain transfer agent may be used to provide free radicals and to control molecular weight distribution. During polymerization, the reaction conditions, e.g., temperature, flow rate, and agitation may be controlled to provide the desired level of conversion.

The relative amount of monomers for the second dispersion also may vary widely. In embodiments where the second polymer is SB, styrene may be present in an amount from 20 to 80 pphm and butadiene may be present in an amount from 20 to 80 pphm. In other embodiments, the styrene may be present in an amount from 5 to 50 pphm, from 10 to 40 pphm, or from 20 to 30 pphm, and butadiene may be present in an amount from 50 to 95 pphm, from 60 to 90 pphm, or from 70 to 80 pphm, based on the total monomer in the second dispersion. Greater styrene to butadiene ratios are also possible. The styrene may be present, for example, in an amount from 40 to 75 pphm, from 55 to 70 pphm, or from 60 to 65 pphm, and butadiene may be present in an amount from 25 to 60 pphm, from 30 to 45 pphm, or from 35 to 40 pphm, based on the total monomer in the second dispersion.

Where the second polymer is SBA, the styrene may be present, for example, in an amount from 30 to 70 pphm, from 40 to 60 pphm, or from 45 to 55 pphm, the butadiene may be present in an amount from 1 to 40 pphm, from 5 to 30 pphm, or from 10 to 25 pphm, and the acrylonitrile may be present in an amount from 5 to 45 pphm, from 15 to 35 pphm, or from 20 to 30 pphm, all based on the total monomer in the second dispersion. For further description of SBA and processes for manufacturing SBA, see Harper C. A., Handbook of Plastic and Elastomers, McGraw-Hill, New York (1975), the entirety of which is incorporated herein by reference.

Adhesive Compositions

The textile structures herein will generally have the latex coating compositions of the invention incorporated thereinto as part of an adhesive composition. Such adhesive compositions can contain, in addition to the latex coating composition hereinabove described, a variety of conventional additives in order to modify the properties thereof. Among these additives may be included fillers, thickeners, catalysts, foaming agents, dispersants, colorants, biocides, antifoaming agents, etc. The textile structures which contain the adhesive compositions prepared from the latex coating compositions described herein can have a weight per unit area of from about 1000 to 4000 g/m², e.g., from 1000 to 3000 g/m².

The viscosity of the adhesive composition may vary widely depending primarily on the desired use of the composition. In general terms, the adhesive composition may have a viscosity ranging from 2,000 to 60,000 cP. Lower viscosities, e.g., from 4000 to 15000 cP, may be preferred for adhesive compositions for use in precoat applications. For skip coat applications, viscosities of 10,000 to 18,000 cP, may be desired for coaters using a roller and pan process, and viscosities from 25,000 to 45,000 cP or higher may be desired for Tilitson-type coaters. The latex coating composition or adhesive composition described herein may also contain sufficient alkali to maintain a pH of between 6 and 10, more preferably between 7 and 9.

Thus, in another embodiment, the invention is directed to an adhesive composition, preferably a carpet precoat or skipcoat binder, comprising an aqueous surfactant-stabilized, copolymer latex coating composition, and sufficient alkali to achieve a pH of 6 to 10, the latex coating composition having dispersed therein a first copolymer of an alkanoic acid having from 1 to 13 carbon atoms and ethylene, and a second copolymer of at least styrene and butadiene, wherein the latex coating composition is stabilized with anionic and/or non-ionic emulsifiers. Preferably, the latex coating composition is formed as a blend of a first dispersion comprising a VAE copolymer and a second dispersion comprising at least styrene and butadiene, as described above. The composition preferably is substantially free of APEs.

The latex coating compositions of the present invention, and the performance of such latex coating compositions in carpet compositions, are illustrated by way of the following non-limiting Examples.

EXAMPLES 1-4

Several blended latex coating compositions were prepared by blending various VAE dispersions, as indicated in Table 1, with SB dispersions at different ratios to test for their compatibility with one another. The SB dispersion employed in Examples 1-4 was Rovene 4487 (Mallard Creek Polymers), an SB dispersion having a solids content from 54.5 to 55.5 wt. %, a styrene to butadiene weight ratio of about 62:38, a Brookfield Viscosity of from 200 to 1500 cps, and a Tg of about +11° C.

The formulations and ratios are provided below in Table 1 for Examples 1-4. Each example was run with a different VAE and/or SB and at several different VAE:SB ratios, as well as different filler loadings, as indicated in Table 1. Examples 1-4 also include unblended VAE-based binders and unblended SB-based binders for comparison. All amounts indicated in the table are Dry Parts by Weight.

TABLE 1 VAE/SB Blend Formulations A B C D Example 1 Surfactant Stabilized VAE 100 50 75 0 SB 0 50 25 100 Filler Load 500 500 500 500 Example 2 Surfactant Stabilized VAE 100 50 75 0 SB 0 50 25 100 Filler Load 600 600 600 600 Example 3 Surfactant and HEC Stabilized VAE 100 50 SB 0 50 Filler Load 500 500 Example 4 Surfactant and PVOH Stabilized VAE 100 50 SB 0 50 Filler Load 500 500

Various viscosity measurements were made for each Example to determine VAE/SB compatibility, as shown in Table 2. Initial viscosity reflects the blended binder viscosity just prior to filler addition. Final viscosity includes filler in the amounts shown in Table 1. After filler addition, the blended binders were allowed to sit under ambient conditions without stirring for 24 hours, and the 24 hour unstirred viscosity was determined, followed by stirring for about 5 minutes and determination of the 24 hour stirred viscosity. Table 2 also shows the amount of thickener (sodium polyacrylate thickener, CT 1015) added to the various binder formulations.

TABLE 2 VAE/SB BLENDED BINDER STABILITY ANALYSIS Initial Final 24 hr 24 hr Viscosity Thickener Viscosity Unstirred Stirred Example (cps) (g) (cps) Visc (cps) Visc (cps) 1A 2,200 5.2 9,800 15,200 10,600 1B 1,600 3.5 9,800 14,000 10,800 1C 2,000 4.1 9,800 15,200 10,600 1D 1,600 3.4 9,900 12,400 11,000 2A 2,000 6.3 9,800 16,800 10,800 2B 1,200 5.0 9,900 14,500 10,600 2C 1,400 5.5 9,000 13,200 9,400 2D 1,000 3.5 9,800 13,600 9,700 3A 7,800 0.8 9,000 11,000 5,000 3B 2,100 2.9 10,800 11,200 9,400 4A 3,600 5.5 9,200 19,500 10,400 4B 11,000 0 9,000 13,000 13,000

Due to its particularly high initial viscosity, 3.2 grams of water was added to Example 4B without any added thickener. The high initial viscosity of Example 4B when compared to the other examples indicates that surfactant stabilized VAE dispersions were surprisingly and unexpectedly more compatible with SB than PVOH stabilized VAE dispersions. The results presented in Table 2 show that polyvinyl alcohol stabilized VAE was not compatible with SB. Blends having higher viscosities, an indication of instability, were not further tested for precoat compound stability.

Precoat binders were then formulated for blends having acceptable viscosities according to the formulation shown in Table 3.

TABLE 3 PRECOAT BINDER FORMULATION Parts by Weight Ingredient (dry) Parts by Weight (Wet) Binder at 55 wt. % Solids 100.0 181.8 Tamol 731 Dispersant 0.5 2.0 Calcium Carbonate 500.0 500.0 Water 0.0 36.6 Froth Aid 1.8 6.0 Thickener As needed for 9000-10000 cPs viscosity (Brookfield at 20 rpm)

The precoat binders were formed to a solids level of 84 wt. % and a target viscosity of 9000-10,000 cPs. Once formed, the precoat binders were applied as a precoat on Beaulieu carpet (made from 300 denier polypropylene fibers with fiber face weight of 20 oz/sq yd (678 g/m²)) at about 22-24 oz/sq yd (746-813 g/m²) target coat weight. The resulting precoat binders were then dried and the carpet samples tested for tuft bind values and are reported in Table 4.

TABLE 4 AVERAGE TUFT BIND DATA No. AVG Coat AVG Tuft Samples Weight Bind Example Tested oz/yd² (g/m²) lbf (N) 1A 4 23.1 (782) 5.6 (25) 1B 4 22.1 (748) 7.2 (32) 1C 4 22.3 (755) 6.0 (27) 1D 2 22.2 (752) 8.0 (36) 2A 3 22.1 (748) 4.5 (20) 2B 3 22.1 (748) 5.2 (23) 2C 3 23.1 (782) 5.0 (22) 2D 3 22.9 (775) 6.0 (27) 3A 4 22.5 (762) 4.6 (20) 3B 2 23.8 (806) 7.1 (32) 4A 3 22.0 (745) 5.6 (25) 4B 2 23.8 (806) 4.5 (20)

As shown in Table 4, several blended precoat binders, in particular those of Examples 1B and 3B, exhibited particularly surprising and unexpectedly high tuft bind values.

EXAMPLE 5

In Example 5A, several VAE/SB dispersion blends were prepared, in different ratios, from two different VAEs and two different SBs. The VAE in Example 5A (VAE 1) was stabilized with 2.5 parts by weight surfactant and 2.5 parts by weight polyvinyl alcohol, while the VAE in Example 5B (VAE 2) was stabilized with 4.5 parts by weight polyvinyl alcohol and 0.5 parts by weight surfactant. Viscosity measurements were then obtained over time to determine relative stability of the dispersion blends. The relative compositions and viscosity results are provided in Tables 5 and 6, respectively, for Examples 5A and 5B. Without being bound by theory, the high polyvinyl alcohol content of the VAE in Example 5B appeared to increase viscosity of the resulting dispersion blends, reflecting an increased incompatibility with SB.

TABLE 5 FORMULATIONS AND VISCOSITIES FOR EXAMPLE 5A Solids VAE:SB Wt. Ratio (wt. %) 50/50 70/30 90/10 50/50 70/30 90/10 VAE 1 62.6 79.9 111.8 143.8 79.9 111.8 143.8 SB 1 52.9 94.5 56.7 18.9 0.0 0.0 0.0 (GenCal 7555) SB 2 53.0 0.0 0.0 0.0 94.3 56.6 18.9 (Rovene 4487) Water 47.8 53.7 59.5 48.0 53.8 59.6 Total 222.2 222.2 222.2 222.2 222.2 222.2 pH 7.2 7 6.3 7 7.8 5.8 Viscosity (cps) Initial 40 40 30 60 45 30  1 Day 40 40 25 80 40 35  3 Days 20 40 25 70 50 35  7 Days 20 40 30 60 80 30 14 Days 20 40 20 50 90 25

TABLE 6 FORMULATIONS AND VISCOSITIES FOR EXAMPLE 5B Solids VAE:SB Wt. Ratio (wt. %) 50/50 70/30 90/10 50/50 70/30 90/10 VAE 2 60.0 83.3 116.7 150.0 83.3 116.7 150.0 SB 1 52.9 94.5 56.7 18.9 0.0 0.0 0.0 (GenCal 7555) SB 2 53.0 0.0 0.0 0.0 94.3 56.6 18.9 (Rovene 4487) Water 44.3 48.8 53.3 44.5 48.9 53.3 Total 222.2 222.2 222.2 222.2 222.2 222.2 pH 7.1 6.7 5.4 6.8 6.2 5 Viscosities (cps) Initial 580 3,500 480 1,060 7,200 2,750  1 Day 410 3,150 420 850 6,500 2,100  3 Days 430 3,500 460 800 7,200 2,600  7 Days 410 3,700 480 840 6,700 2,800 14 Days 400 3,950 550 875 7,200 2,500

While the illustrative embodiments of the disclosure have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of the patentable novelty which reside in the present disclosure, including all features which would be treated as equivalents thereof by those skilled in the art to which the disclosure pertains. 

We claim:
 1. A carpet product comprising at least one substrate and at least one adhesive layer associated with said at least one substrate, said adhesive layer being formed from a latex coating composition comprising: (a) a first copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene; and (b) a second copolymer of at least styrene and butadiene, wherein the first and second copolymers are colloidally dispersed in an aqueous medium comprising a surfactant.
 2. The carpet product of claim 1, wherein the at least one adhesive layer associated with the at least one substrate is a precoat layer that binds carpet fibers to the substrate.
 3. The carpet product of claim 1, wherein the at least one adhesive layer associated with the at least one substrate is a skipcoat layer that binds a primary backing layer to a secondary backing layer.
 4. The carpet product of claim 1, having a tuft bind value greater than 20 N.
 5. The carpet product of claim 1, having a tuft bind value greater than 27 N.
 6. The carpet product of claim 1, having a tuft bind percentage, as defined herein, greater than 150%.
 7. The carpet product of claim 1, wherein the first copolymer is present in an amount from 30 to 99 wt. % and the second copolymer is present in an amount from 1 to 70 wt. %.
 8. The carpet product of claim 1, wherein the first copolymer is present in an amount from 40 to 75 wt. %, and the second copolymer is present in an amount from 25 to 60 wt. %.
 9. The carpet product of claim 1, wherein the first copolymer is a copolymer of the vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms, ethylene, and an acrylic monomer or ester thereof.
 10. The carpet product of claim 1, wherein the first copolymer comprises a copolymer of vinyl acetate, vinyl neodecanoate and ethylene.
 11. The carpet product of claim 1, wherein the first copolymer has an average particle size from 100 to 400 nm, as determined by a 90 Plus Particle Size Analyzer using a 35 mW solid state laser of 658 nm wavelength at room temperature.
 12. The carpet product of claim 1, wherein the second copolymer is a copolymer of styrene, butadiene and acrylonitrile.
 13. The carpet product of claim 1, wherein either the first copolymer or the second copolymer further comprises a polyethylenically unsaturated co-monomer selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, diallyl maleate, diallyl fumarate, divinyl benzine, diallyl phthalate, silanes, and GMA.
 14. The carpet product of claim 1, wherein the adhesive layer further comprises a filler selected from the group consisting of kaolin clay, calcium carbonate, ATH aluminum trihydrate, recycled fillers, ground glass, silica, fly ash, and combinations of said fillers.
 15. The carpet product of claim 1, wherein the latex coating composition is stabilized with at least one of an anionic or nonionic surfactant.
 16. The carpet product of claim 1, wherein the first copolymer comprises from 75 to 95 pphm vinyl acetate and from 5 to 25 pphm of ethylene.
 17. The carpet product of claim 16, wherein the second copolymer comprises from 20 to 80 pphm of styrene and from 20 to 80 pphm of butadiene.
 18. The carpet product of claim 1, wherein the second copolymer comprises from 20 to 80 pphm of styrene and from 20 to 80 pphm of butadiene.
 19. The carpet product of claim 1, wherein the latex coating composition has a solids content of from 40 to 70 wt. %.
 20. The carpet product of claim 1, wherein the latex coating composition comprises a blend of a first dispersion comprising the first copolymer and a second dispersion comprising the second copolymer.
 21. The carpet product of claim 20, wherein the first dispersion comprises less than 1.0 pphm polyvinyl alcohol.
 22. The carpet product of claim 20, wherein the first dispersion comprises less than 0.5 pphm polyvinyl alcohol.
 23. The carpet product of claim 20, wherein the first dispersion comprises less than 1.0 wt. percent polyvinyl alcohol, based on the total weight of all monomers.
 24. The carpet product of claim 1, wherein the first and second copolymers are not intimately mixed.
 25. The carpet product of claim 1, wherein the adhesive composition has a viscosity from 2,000 to 60,000 cP.
 26. The carpet product of claim 1, wherein the latex coating composition has a final viscosity, as defined herein, that does not increase by greater than 50% after 48 hours.
 27. The carpet product of claim 1, wherein the latex coating composition further comprises hydroxyethyl cellulose.
 28. A process for forming a carpet product, the process comprising the steps of: (a) providing an adhesive composition comprising a latex coating composition, comprising: (i) a first copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene; and (ii) a second copolymer of at least styrene and butadiene, wherein the first and second copolymers are colloidally dispersed in an aqueous medium comprising a surfactant; (b) contacting carpet fibers with a primary backing material; (c) applying the adhesive composition to the carpet fibers and the primary backing material; and (d) drying the adhesive composition under conditions effective to adhere the carpet fibers to the primary backing material.
 29. The process of claim 28, wherein the carpet product has a tuft bind value greater than 20 N.
 30. The process of claim 28, wherein the carpet product has a tuft bind value greater than 27 N.
 31. The process of claim 28, wherein the carpet product has a tuft bind percentage, as defined herein, greater than 150%.
 32. The process of claim 28, wherein the first copolymer is present in an amount from 30 to 99 wt. % and the second copolymer is present in an amount from 1 to 70 wt. %.
 33. The process of claim 28, wherein the first copolymer is present in an amount from 40 to 75 wt. %, and the second copolymer is present in an amount from 25 to 60 wt. %.
 34. The process of claim 28, wherein the first copolymer comprises a copolymer of vinyl acetate, vinyl neodecanoate and ethylene.
 35. The process of claim 28, wherein the first copolymer has an average particle size from 100 to 400 nm, as determined by a 90 Plus Particle Size Analyzer using a 35 mW solid state laser of 658 nm wavelength at room temperature.
 36. The process of claim 28, wherein the second copolymer is a copolymer of styrene, butadiene and acrylonitrile.
 37. The process of claim 28, wherein the first copolymer is a copolymer of the vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms, ethylene, and an acrylic monomer or ester thereof.
 38. The process of claim 28, wherein either the first copolymer or the second copolymer further comprises a polyethylenically unsaturated co-monomer selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, diallyl maleate, diallyl fumarate, divinyl benzine, diallyl phthalate, silanes, and GMA.
 39. The process of claim 28, wherein the adhesive composition further comprises a filler selected from the group consisting of kaolin clay, calcium carbonate, ATH aluminum trihydrate, recycled fillers, ground glass, silica, fly ash, and combinations of said fillers.
 40. The process of claim 28, wherein the latex coating composition is stabilized with at least one of an anionic or nonionic surfactant.
 41. The process of claim 28, wherein the first copolymer comprises from 75 to 95 pphm vinyl acetate and from 5 to 25 pphm of ethylene.
 42. The process of claim 41, wherein the second copolymer comprises from 20 to 80 pphm of styrene and from 20 to 80 pphm of butadiene.
 43. The process of claim 28, wherein the second copolymer comprises from 20 to 80 pphm of styrene and from 20 to 80 pphm of butadiene.
 44. The process of claim 28, wherein the latex coating composition has a solids content of from 40 to 70 wt. %.
 45. The process of claim 28, wherein the latex coating composition comprises a blend of a first dispersion comprising the first copolymer and a second dispersion comprising the second copolymer.
 46. The process of claim 45, wherein the first dispersion comprises less than 1.0 pphm polyvinyl alcohol.
 47. The process of claim 45, wherein the first dispersion comprises less than 0.5 pphm polyvinyl alcohol.
 48. The process of claim 45, wherein the first dispersion comprises less than 1.0 wt. percent polyvinyl alcohol, based on the total weight of all monomers.
 49. The process of claim 28, wherein the first and second copolymers are not intimately mixed.
 50. The process of claim 28, wherein the adhesive composition has a viscosity from 2,000 to 60,000 cP.
 51. The process of claim 28, wherein the latex coating composition has a final viscosity, as defined herein, that does not increase by greater than 50% after 48 hours.
 52. The process of claim 28, wherein the latex coating composition further comprises hydroxyethyl cellulose.
 53. A process for forming a carpet product, the process comprising the steps of: (a) providing an adhesive composition comprising a latex coating composition comprising: (i) a first copolymer of at least a vinyl ester of an alkanoic acid having from 1 to 13 carbon atoms and ethylene; and (ii) a second copolymer of at least styrene and butadiene, wherein the first and second copolymers are colloidally dispersed in an aqueous medium comprising a surfactant; (b) providing a primary carpet layer comprising yarn tufted into a primary backing material; (c) applying the adhesive composition to at least one of the primary carpet layer or a secondary backing; (d) contacting the primary carpet layer with the secondary backing; and (e) drying the adhesive composition under conditions effective to adhere the primary carpet layer to the secondary backing.
 54. The process of claim 53, wherein a precoat layer binds the yarn to the primary backing material.
 55. The process of claim 53, wherein the precoat layer comprises the same latex coating composition as the adhesive composition. 